An aircraft can be equipped with a fire extinguishing system to spray a chemical agent into an engine compartment to extinguish a fire. Traditional fire extinguishing agents, such as Halon 1301, discharge thoroughly at low temperatures and therefore are useful for aircraft fire extinguishing where the agent can be exposed to cold weather and high altitudes. However, these agents are currently being phased out. Replacement agents are available which are effective at extinguishing fires in many respects, but which do not perform as well as traditional agents in low temperatures. Therefore, aircraft manufacturers seek improved fire extinguishing performance in low temperatures.